Exhaust brake valve

Abstract

An exhaust brake valve assembly structurally arranged to provide reliable operation with relatively quick response. The assembly includes a sliding gate valve member driven by a power actuator through a lost motion connection which generates a desirable impact force on the gate to overcome static frictional forces. The lost motion connection cooperates with a relief port in the gate to relieve peak pressure forces on the gate just prior to opening movement to additionally improve opening reliability and response. Still further, the actuator includes a spring return arrangement in which the force rate adjacent the closed gate position is substantially greater than the force rate at the open position so that adequate reserve return force is developed for opening while only a minimal spring force resists piston movement in the initial opening movement. A quick release valve is provided on the actuator to rapidly exhaust fluid from the working chamber of the actuator to develop a high level of kinetic energy during the lost motion period. The actuator is protected from extreme temperature by a heat barrier plate interposed between the valve housing and actuator. A piston rod of the actuator is sealed by a radially floating seal and includes a reduced diameter portion and opposed shoulders for simple connection with the valve gate.

What is claimed is: 
     
       1. An exhaust brake valve comprising a housing having an inlet and outlet, a passage within said housing providing a gas flow path between said inlet and outlet, a valve seat within said housing defining a peripheral boundary around said passage, a valve member in said housing adapted to close said valve seat to restict said passage, a control member adapted to be connected to a power actuator external of said housing for selectively opening and closing said valve member on said valve seat, lost motion connection means between said valve member and said control member, and means for adjustably limiting the closed position of said valve member to less than complete sealing engagement with said seat, said limiting means including means operative to effect selective postioning of said valve member for limiting closure on said seat independently of said lost motion connection means, said operative means being disposed within said housing and being directly engageable with said valve member, said valve member being a generally planar gate slidably disposed for reciprocation in its plane between its open and closed positions, said lost motion connection means being constructed and arranged to provide an amplitude of lost motion in the order of about one-eighth of the displacement of the valve member between its open and closed positions. 
     
     
       2. A valve as set forth in claim 1, wherein said limiting means is a threaded stop member extending through an end wall of the housing into the path of said gate, the longitudinal axis of said threaded member being parallel to the direction of reciprocation of said valve member. 
     
     
       3. A valve as set forth in claim 2, wherein said control member is a rod mounted relative to said housing for reciprocation along its axis, said threaded member being substantially coaxial with said rod. 
     
     
       4. A valve as set forth in claim 1, including a power actuator, said actuator having piston means responsive to fluid pressure to close said valve member, and spring means resisting movement of said piston means and biasing said valve member towards its open position. 
     
     
       5. An exhaust brake valve comprising a housing having an inlet and outlet, a passage within said housing providing a gas flow path between said inlet and outlet, a valve seat within said housing defining a peripheral boundary around said passage, a valve member in said housing adapted to close said valve seat to restrict said passage, a control member adapted to be connected to a power actuator external of said housing for selectively opening and closing said valve member on said valve seat, lost motion connection means between said valve member and said control member, and means for adjustably limiting the closed position of said valve member to less than complete sealing engagement with said seat, said lost motion connection means including a secondary valving member, said first-mentioned valve member including a relief port, said secondary valving member being adapted to seal said relief port when said first-mentioned valve is in its closed position, and being adapted to open said relief port when said control member initiates opening movement of said first-mentioned valve member. 
     
     
       6. In an exhaust system of an internal combustion engine a compression brake valve for an internal combustion engine comprising a housing having an inlet and an outlet, a passage within said housing providing a gas flow path between said inlet and outlet, a valve seat within said housing defining a peripheral boundary on said passage, a valve member in said housing adapted to close the valve seat, a control member adapted to be connected to power actuating means external of said housing and operatively connected to said valve member for selectively and forcibly opening and closing said valve member on said valve seat between open and closed positions, means for adjustably limiting the closed position of said valve member to less than complete sealing engagement with said seat, said limiting means including an element within said housing in direct engagement with said valve member when the valve member is in its closed position, and lost motion connection means interposed between said control member and said valve member, said lost motion connection means being constructed and arranged to provide an amplitude of lost motion in the order of about one-eighth of the displacement of the valve member between its open and closed positions. 
     
     
       7. An exhaust brake valve comprising a housing having an inlet and an outlet, a passage within said housing providing a gas flow path between said inlet and outlet, a valve seat in said housing defining a peripheral boundary around said passage, a valve member in said housing adapted to close said valve seat to restrict said passage, a control member for selectively opening and closing said valve member on said seat, power actuator means external of said housing for moving said valve member through said control member, said actuator means including piston means responsive to fluid pressure for closing said valve member, spring means resisting movement of said piston means and biasing said valve member towards its open position, said spring means including means for substantially increasing the rate of biasing force for opening said valve member in or adjacent its closed position compared to the force rate applied by said spring means to bias the valve member when the valve member is in its open position, said spring means including first and second springs operative to bias said valve member, the second spring having a length substantially shorter than the operating length of the first spring and being arranged to bias said valve member only when said valve member is in or adjacent its closed position, said second spring having a compression rate substantially greater than said first spring. 
     
     
       8. A valve as set forth in claim 7, wherein said valve member is a slide gate, said control member being a rod connected between said piston means and said gate, said springs being coaxially arranged with said rod. 
     
     
       9. An exhaust brake valve comprising a housing having an inlet and outlet, a passage within said housing providing a gas flow path between said inlet and outlet, a valve seat within said housing defining a peripheral boundary around said passage, a sliding gate valve member in said housing adapted to close said valve seat to restrict said passage, a power actuator external of said housing for selectively opening and closing said valve member on said valve seat, said actuator including piston and cylinder means responsive to fluid pressure for closing said valve member, a piston rod connected to the piston of said piston and cylinder means and extending axially through the cylinder of said piston and cylinder means, lost motion connection means between said piston rod and said valve member, said actuator including spring means resisting movement of the piston and biasing said valve member towards its open position, said spring means including a first spring within the cylinder and concentric about said piston rod, said first spring being arranged to operate on said piston substantially through its full stroke, said spring means including a second spring within the cylinder and concentric about said piston rod, said second spring being arranged to operate on said piston only when said piston is in or adjacent a valve member closing position, said spring means substantially increasing the rate of biasing force for opening said valve member in or adjacent its closed position compared to the force rate applied by said spring means to bias the valve member when the valve member is in or adjacent its open position, said spring means being capable of fully opening said valve member. 
     
     
       10. An exhaust brake valve as set forth in claim 9, including adjustment means for selectively limiting the closed position of said valve member, said adjustment means including an element within said housing directly engageable with said valve member. 
     
     
       11. An exhaust brake valve as set forth in claim 10, wherein said valve member includes a relief port therethrough, said lost motion connection means including means to seal said relief port when said valve member is moved to said closed position and open said relief port when said valve member is moved to said open position. 
     
     
       12. An assembly comprising an exhaust brake valve and a power actuator for controlling the exhaust brake valve, said brake valve including a housing, means for mounting said actuator on a face of said housing, heat barrier means for limiting heat conduction from said housing to said actuator, said heat barrier means including projection means spacing said actuator from said housing, said projection means having a cross sectional area substantially less than the area of said housing face, said projection means including a plurality of boss elements spaced laterally about a control rod extending between said actuator and said housing, said boss elements being integral with a plate forming a wall on said housing. 
     
     
       13. An assembly as set forth in claim 12, wherein said actuator is secured to said housing by mounting bolts extending into a plurality of said bosses. 
     
     
       14. In combination, an exhaust brake valve having a valving element operable between an open and closed position to selectively restrict flow of exhaust gas, a fluid power actuator, means connecting said fluid power actuator to said valving element for moving said valving element between said open and closed positions, said connecting means including lost motion means between said actuator and said valving element, a control line connected to said fluid power actuator for supplying pressurized fluid to a working chamber of said actuator, and control means for quickly releasing fluid from said chamber through a path separate from said control line, said separate path including an exhaust port immediately adjacent said actuator, said actuator including spring means for returning said valving element from the closed position to the open position, said spring means being arranged to move a portion of said connecting means during its period of lost motion at a relatively high rate of acceleration due to quick release of fluid by said control means whereby a high level of kinetic energy is developed to reliably open said valving element. 
     
     
       15. The combination as set forth in claim 14, wherein said valving element is a sliding gate, said actuator having a piston and cylinder, and said connecting means includes a piston rod. 
     
     
       16. The combination as set forth in claim 15, wherein said quick release control means includes a valve carried on said actuator. 
     
     
       17. An assembly comprising an exhaust brake valve and an actuator, said valve having a housing including a wall at one side thereof, a plate for mounting said actuator on said valve housing, said wall and plate providing opposed spaced surfaces, a control rod extending through holes in said wall and plate surfaces, a seal around said piston rod, said seal being axially compressed between said surfaces, said seal having a compressed axial length at said rod substantially limited to the spacing between said surfaces and thereby being free to move laterally with respect to said holes to remain concentric with said control rod. 
     
     
       18. An assembly as set forth in claim 17, wherein said seal is an assembly of a high temperature sealing material and an annular band radially engaging and confining said material, said band having an axial length slightly less than the spacing between said surfaces. 
     
     
       19. An exhaust brake valve comprising a housing having an inlet and outlet, a passage within said housing providing a gas flow path between said inlet and outlet, a valve seat within said housing defining a peripheral boundary around said passage, a valve member in said housing adapted to close said valve seat to restrict said passage, a control member adapted to be connected to a power actuator external of said housing for selectively opening and closing said valve member on said valve seat, lost motion connection means between said valve member and said control member, and means for adjustably limiting the closed position of said valve member to less than complete sealing engagement with said seat, said limiting means including means operative to effect selective positioning of said valve member for limiting closure on said seat independently of said lost motion connection means, said operative means being disposed within said housing and being directly engageable with said valve member, said valve member being a generally planar gate slidably disposed for reciprocation in its plane between its open and closed positions, a power actuator, said actuator having piston means responsive to fluid pressure to close said valve member, and spring means resisting movement of said piston means and biasing said valve member towards its open position, said spring means including means for substantially increasing the rate of biasing force for opening said valve member when said valve member is in or adjacent its closed position compared to the force rate applied by said spring means to bias the valve member towards its open position when the valve member is adjacent its open position.